Tramway rope displacement indicator



7 0a. 17, 1967 R, SOW ER 3,347,172

TRAMWAI ROPE DISPLACEMENT INDICATOR Filed July 15, 1963 'N 2 8 LT.

a w M N I I INVENTOR. g TONY R.SOWDER United States Patent 3,347 172 TRAMWAY ROPE DISPLACEMENT INDICATOR Tony R. Sowder, Spokane, Wash, assignor to Riblet Tramway Company, Spokane, Wash, a corporation of Washington Filed July 15, 1963, Ser. No. 295,048 2 (Ilaims. (Cl. 1ll4-173) This invention relates in general to an aerial tramway having a circulating rope and in particular in an indicator for annunciating the displacement of the circulating traction rope with respect to any of its guide sheaves.

Aerial tramways conventionally include at least one endless circulatng traction rope trained about a powered drive sheave at one end mounted on a drive terminal and at the other end an idling tension sheave mounted on a carriage forming a part of the tension terminal and adapted to maintain tension on the traction rope. Also conventionally a plurality of rope guiding the towers intermediate the two terminals are provided and are designed to control the circulating movement of the traction rope over its entire path. These towers are provided with rope guiding sheaves which are primarily disposed in vertical planes and either support the circulating traction rope or depress the rope as required. Less frequently sheaves disposed in horizontal or oblique planes are employed under peculiar circumstances. 7 Since many aerial tramways are of the type employed to carry aerial ski-lift chairs, the collection of snow and ice on the working parts is a condition with which one is concerned. After a period of inoperation in below freezing temperatures ice may collect on the immobilized parts so that when the tramway is again mobilized the ice must be broken away by the movement of the traction rope and the subsequent movement of the relative parts.

In some instances ice forming upon a cable will cause the cable to jump out of its desired path with respect to the guiding sheaves. At other times during the'operation of the tramway high winds may exert excessive lateral loads upon the cable and cause its accidental displacement from the guiding sheaves. In the event of the displacement of a traction rope from whatever cause, it is desirable if not absolutely necessary that this displacement be immediately known to the operator.

It is therefore an object of the present invention to provide an indicator by means of which an operator may be informed of the displacement of the traction rope with respect to its guiding sheaves irrespective of the location of said displacement along the circulating traction rope.

It is known to employ sensing devices which are disposed to be struck by the traction rope when it is shifted from its proper placement with respect to its guiding sheaves. However when ice forms upon the traction rope its circumference may be sutficiently increased to strike the sensing device and thus give an inaccurate indication of displacement to the tramway operator. Since normally traction ropes are provided with spindles or other attachments for supporting ski-lift chairs, or transport buckets, etc., the sensing devices of the prior art cannot completely encircle the traction rope but are normally disposed at no more than three sides of the traction rope and in most instances only one side, i.e., that side in the direction which the traction rope is most apt to deflect when displaced from its proper relationship to the guide sheaves. It has been found however that in some instances these prior arts sensing devices are inadequate since the lateral loads applied to cables by winds and other forces tending to cause a cable to swing can cause them to miss completely the sensing device upon being displaced from their guiding sheaves and thus fail to give any indication of a displaced rope when such indication is required.

3,347,172 Patented Oct. 17, 1967 It is therefore a further object of the present invention to provide a tramway rope displacement indicator which is designed to properly function at any time when the tramway rope is displaced from its predetermined relative position to any or all of the rope guiding sheaves.

Another object of the present invention lies in the provision of means for indicating displacement of a tramway rope which means is maintained in an inoperative position by the proper placement of the circulating traction rope and operable to annunciate displacement of the rope by its inherent bias to move to an indicating position when not restrained by said circulating rope.

It is yet another object of the present invention to provide a tramway rope displacement indicator which is not rendered inoperative by the normal accumulation of ice and snow under adverse conditions.

Further objects of the present invention will become apparent from the following description when considered in conjunction with the accompanying drawings wherein:

FIGURE 1 is an elevational view of a guide sheave tower having a depression sheave assembly;

FIGURE 2 is an enlarged fragmentary elevational view taken from FIGURE 1, parts broken away for convenience of illustration; and

FIGURE 3 is a schematic wiring diagram.

In the embodiment of the invention shown, the numeral 10 indicates in its entirety an endless circulating traction rope of an aerial tramway, only a portion of which is shown, and associated with a depression sheave assembly 12 mounted upon an intermediate tower 14. In this illustration the natural tendency of the traction rope 10 is to raise above the full line position shown. Therefore the depression sheaves 1616 are disposed in a horizontal plane above the tract-ion rope 10 and are journaled on horizontal axes 1818 for rotation as the traction rope 10 circulates and causes the sheave 16 to roll upon the tramway rope 10.

The sheaves 16 conventionally are provided with an annular groove not shown, which groove receives at least half and preferably more of the diameter of the traction rope 10. Other sheaves 20 journaled at 22 are disposed diametrically of the traction rope 10 from the sheave 16 to confine the rope in its desired path with respect to the guide sheaves 16.

The journals 18 and 22 of the several sheaves are mounted on sheave frames 24, shown in a first position, which are disclosed to be rotatably mounted on journals 26 extending axially parallel to the journals 18 and 22 from the ends of an evener frame 23 which is rotatably mounted upon further journal 30 mounted on the tower 14 and disposed axially parallel to the journals 18, 22 and 26.

Obviously if desired a single sheave frame 24 may be mounted on the journal 30 thus omitting the evener frame 28 and the second identical sheave frame 24. But for most installations to provide proper control of the circulating path of the circulating traction rope 10 I employ the device substantially as shown. It will thus be seen that where the moment applied from the traction rope 10 to the depression sheave assembly 12 is upwardly the traction rope 10 is maintained in a desired path against upward displacement by the several sheaves 16.

Slight variations occasioned by a heavy load being carried by the wire rope 10, as in the fore-mentioned events of ski-lift chairs or ore hauling buckets, will be compensated by limited pivotal movement of the sheave frames 24 about their journals 26 and similar movements of the evener frames 28 about their journal 30.

Each of the sheave frames 24 is yieldably biased toward a second position wherein it is rotated about its journal 26 for a fraction of a complete circle. In the embodiment shown this rotation will be approximately 30 in the di- 9 rection of the arrows indicated by the reference numerals 3232'. This bias may be in the form of an overbalancing weight differential. For example, two sheave wheels 16 are disposed above a single sheave 20. -Alternately if the weight is normally disposed below the journal 26, as in a supporting sheave assembly (not shown) an additional overbalancing weight 34 may be supplied to bias the sheave frame 24 for rotation. Complementary thereto or as an alternate means I may provide the bias by means of an induced mechanical bias as'indicated by the application of a tension spring 36. Of course any means for providing the bias by which'the sheave frame 24 is caused to rotate from its first position and thus displace a journal 18 of a traction rope guiding sheave 16, with respect to its support, will be sufficient to provide movement to activate annunciating means 36, disclosed in FIGURE 3.

In said annunciating means 36 a source of electrical power 38 is connected in an electrical circuit 40 to energize an annunciator 42 here seen to'be a visible light but which may take the form of an audible indicator. The circuit also includes any number of circuit control switches 4444 connected in parallel to each other. In FIG- URE 3 I have shown two switches one of which'is to be attached to each of the sheave frames 24 as shown in FIGURE 2 of the drawing.

The'switches 44 are preferably of the mercury type and each is fixed upon a segment 46 of a disc. A fastening means, for example, stub bolt 48, is provided to pivotally mount the segment on the sheave frame 24 and an anchoring means such as an additional bolt 50 is'provided to adjustably fix the segment to the sheave frame 24 in a selected adjusted position within its .arcuate travel limits as indicated by the arrows 52-52. The bolt 50 passes through the arcuate slot 54 formed in the segment so that by loosening said bolt 50 the angular position of the mercury'switch 44 with respect to thehorizontal when the traction rope is emplaced with respect to its guide sheave 16 is adjusted and fixed so that the electrical cir' cuit is open. Then when the cable is displaced and moved for example from the full line position of FIGURE 1 to the dotted line position the bias, for example 34 or 36, causes the journal 18 to move as'shown by arrow 32 thus making connection in-the control switch 44 and actuating the annunciator 42 for observation by the tramway operator.

While I have shown a pivotal motion, it will be understood that other lost motion connection between the journal 18 and the tower 14 may supplant the lost motion connection embodied in the pivotally mounted sheave frame24.

Having thus described my invention I desire to secure by Letters Patent of the United States the following:

1. In an aerial tramway having an endless circulating traction rope guided by rope supporting sheaves supported on towers, means of the nature aforesaid'for indicating dis-placement of said rope from its predetermined relationship with said rope supporting sheaves, comprising, in combination:

a sheave frame journaled on a substantially horizontal axis on said tower, for tilting in a substantially vertical plane;

more than one rope supporting sheave journaled on said sheave frame for rotation in a plane substantially parallel to the plane of said tilting movement with the axis of at least one of said sheaves laterally 4 offset from a line throughsaid sheave journal and the point of contact of said traction rope with the immediately aforesaid sheave so that force of said traction rope maintains said sheave frame in a first normal pivotal position;

means of yieldably biasing said sheave frame to a second pivotal position comprising a mechanical force existing between said sheave frame and said tower member;,and

an annunciator adapted to activate upon tilting movement of said sheave frame from said first normal position to signal such event, characterized by an electrically energized signaling device supplied with energy through a series connected ;,level sensitive switch carried by said sheave frame to interrupt current only when said frame is moved to said second position.

2. In an aerial tramway having an endless circulating traction rope guided by rope supporting sheaves supported on towers, means of the nature aforesaid for indicating displacement of said rope fromits predetermined relationship with said rope supporting sheaves, comprising, in combination:

a sheave frame journaled on a substantially horizontal axis on said tower, for tilting in a substantially vertical plane;

more than one rope supporting sheave, positioned to support said traction rope from both above and below, journaled on said sheave frame for rotation in a plane substantially parallel to the plane of said tilting movement with the axis of at least one of said sheaves laterally offset from a line through said sheave journal and the point of contact of said traction rope with the immediately aforesaid sheave so that force of said traction rope maintains said sheave frame in a first normal pivotal position;

means of yieldably biasing said-sheave frame to a second pivotal position'comprising a mechanical force existing between said sheave frame and said tower member; and

an annunciator'adapted to activate upon tilting move-.

ment of said sheave frame from said first normal position to signal such event, characterized by an electrically energized signaling device supplied with energy through a series connected level sensitive switch carried by said sheave frame and adapted to interrupt current only when said frameis moved to said second position.

References Cited UNITED STATES PATENTS ARTHUR L. LA POINT, Primary Examiner.

S. B. GREEN, S. T. KRAWCZEWICZ,

Assistant Examiners. 

1. IN AN AERIAL TRAMWAY HAVING AN ENDLESS CIRCULATING TRACTION ROPE GUIDED BY ROPE SUPPORTING SHEAVES SUPPORTED ON TOWERS, MEANS OF THE NATURE AFORESAID FOR INDICATING DISPLACEMENT OF SAID ROPE FROM ITS PREDETERMINED RELATION SHIP WITH SAID ROPE SUPPORTING SHEAVES, COMPRISING IN COMBINATION: A SHEAVE FRAME JOURNALLED ON A SUBSTANTIALLY HORIZONTAL AXIS ON SAID TOWER, FOR TILTING IN A SUBSTANTIALLY VERTICAL PLANE; MORE THAN ONE ROPE SUPPORTING SHEAVE JOURNALED ON SAID SHEAVE FRAME FOR ROTATION IN A PLANE SUBSTANTIALLY PARALLEL TO THE PLANE OF SAID TILTING MOVEMENT WITH THE AXIS OF AT LEAST ONE OF SAID SHEAVES LATERALLY OFFSET FROM A LINE THROUGH SAID SHEAVE JOURNAL AND THE POINT OF CONTACT OF SAID TRACTION ROPE WITH THE IMMEDIATELY AFORESAID SHEAVE SO THAT FORCE OF SAID TRACTION ROPE MAINTAINS SAID SHEAVE FRAME IN A FIRST NORMAL PIVOTAL POSITIONS; 